13- Contributions Of Cerebellum And Basal Nuclei To Motor Function II Flashcards Preview

A. White- Human Physiology > 13- Contributions Of Cerebellum And Basal Nuclei To Motor Function II > Flashcards

Flashcards in 13- Contributions Of Cerebellum And Basal Nuclei To Motor Function II Deck (35):

Is the putamen circuit a(n) indirect/direct basal nuclei circuit?



Is the caudate nucleus circuit a(n) indirect/ direct basal nuclei pathway?



The basal nuclei receive most of their input from the cerebral cortex and return most of their output where?

To the cerebral cortex


What is the principle roles of the basal nuclei?

To work with the corticospinal system to modulate thalamic output to the motor cortex to plan and execute smooth movements


The basal nuclei consist of paired nuclei. What are they?

- striatum (--caudate nucleus-- and the putamen)
- globus pallidus
- substantia nigra
- subthalamic nucleus


Almost all motor and sensory nerve fibers connecting the spinal cord to the cortex pass through the space that lies between the what major masses of the basal nuclei?

The caudate nucleus and the putamen


What is the space between the caudate nucleus and the putamen called?

The internal capsule


The striatum consist of what nuclei?

- caudate nucleus
- putamen


This circuit/pathway is for subconscious execution of learned pattern movements?

- Putamen circuit (direct pathway)


Is the putamen pathway excitatory or inhibitory?

- overall excitatory -- tends to increase motor activity


Connections between the striatum and the substantia nigra use what neurotransmitter?



Dopamine is ___________ on the indirect pathway?

Inhibitory (uses D2 receptors)


Dopamine is __________ on the direct pathway?

Excitatory (uses D1 receptors)


Because of the receptors used in the pathway, the overall effect of dopamine in the putamen circuit (direct pathway) Is what?

Excitatory (uses D1 receptors)


The IGP/SubNigRet is normally ________ and sends __________ signals to the thalamus. Exciting the putamen _________ the IGP/SubNigRet and allows the thalamus to send __________ signals to the motor cortex?

Active, inhibitory. Inhibits, excitatory.


Lesions in the globus pallidus can lead to?

Spontaneous and often continuous writhing movements of a hand, an arm, the neck, or the face----(called Athetosis)


Lesions in the subthalamic nuclei can lead to?

Sudden flailing movements of an entire limb---(called hemiballismus)


Lesions in the striatum (caudate nucleus and putamen) can lead to?

Flicking movements in the hands, face, and other parts of the body---(called chorea)


Lesions in the substantia nigra can lead to?

To the common and extremely severe disease of rigidity, akinesia, and tremors---(aka Parkinson's disease)


Is the caudate circuit (indirect pathway) inhibitory or excitatory?

Overall inhibitory-- tends to decrease motor activity


This circuit/pathway plays a major role in cognitive control of motor activity?

Caudate circuit (indirect pathway)


This pathway/circuit is for cognitive planning of sequential and parallel motor patterns?

Caudate circuit (indirect pathway)


Substantia nigra----> causdate nucleus. What NT?

Dopamine (inhibitory)


Caudate nucleus and putamen---->globus pallidus and substantia nigra. What NT?

GABA (inhibitory)


Cortex---->caudate nucleus and putamen. What NT?

Acetylcholine (excitatory)


What neurotransmitters are involved in multiple pathways from the brain stem?

- norepinephrine
- serotonin (inhibitory)
- encephalin


These pathways provide most of the excitatory signals in the basal ganglia?

Multiple glutamate pathways


What is another name for paralysis agitans?

Parkinson's disease


What are the characteristics displayed by Parkinson's?

- rigidity of much of body musculature
- involuntary tremors of involved areas even at rest at a fixed rate
- serious difficulty in initiating movement (akinesia)
- postural instability
- dysphasia, speech disorders, gait disturbances, fatigue


Parkinson's results from what?

Widespread destruction of pars compacta of substantia nigra that sends dopaminergic fibers the the caudate nucleus and putamen (striatum)


With Parkinson's, dopaminergic pathways to direct and indirect pathways are lost. What does this result in?

-direct pathway (putamen circuit) loses some of its excitatory input
- indirect pathway (caudate circuit) loses some of its inhibitory pathway

** either way there is decrease motor activity**


People with Huntington's disease usually become symptomatic around what age?

30-40 years of age


What are the characteristics displayed by Huntington's?

- flicking movements of individual muscle
- progressive sever distortional movements of entire body
- severe dementia
- motor dysfunctions


What is thought to be the reason for the abnormal movements in those with Huntington's?

- Loss of most of the cell bodies of GABA-secreting neurons of the caudate nucleus and putamen AND of Ach neurons in other parts of the brain

- the axon terminals of the GABA neurons normally inhibit portions of the globus pallidus and substantia nigra. This loss of inhibition is believed to allow spontaneous outbursts of the globus pallidus and substantia nigra activity that cause the distortional movements


What are the 2 major basal nuclei circuits?

- Putamen circuit (direct)
- Caudate nucleus circuit (indirect)